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| Content Provider | PubMed Central |
|---|---|
| Author | Kaufmann, Martin Prosser, David E. Jones, Glenville |
| Copyright Year | 2011 |
| Abstract | CYP24A1 is a mitochondrial cytochrome P450 (CYP) that catabolizes 1α,25-dihydroxyvitamin D3 (1α,25-(OH)2D3) to different products: calcitroic acid or 1α,25-(OH)2D3-26,23-lactone via multistep pathways commencing with C24 and C23 hydroxylation, respectively. Despite the ability of CYP24A1 to catabolize a wide range of 25-hydroxylated analogs including 25-hydroxyvitamin D3, the enzyme is unable to metabolize the synthetic prodrug, 1α-hydroxyvitamin D3 (1α-OH-D3), presumably because it lacks a C25-hydroxyl. In the current study we show that a single V391L amino acid substitution in the β3a-strand of human CYP24A1 converts this enzyme from a catabolic 1α,25-(OH)2D3-24-hydroxylase into an anabolic 1α-OH-D3-25-hydroxylase, thereby forming the hormone, 1α,25-(OH)2D3. Furthermore, because the mutant enzyme retains its basal ability to catabolize 1α,25-(OH)2D3 via C24 hydroxylation, it can also make calcitroic acid. Previous work has shown that an A326G mutation is responsible for the regioselectivity differences observed between human (primarily C24-hydroxylating) and opossum (C23-hydroxylating) CYP24A1. When the V391L and A326G mutations were combined (V391L/A326G), the mutant enzyme continued to form 1α,25-(OH)2D3 from 1α-OH-D3, but this initial product was diverted via the C23 hydroxylation pathway into the 26,23-lactone. The relative position of Val-391 in the β3a-strand of a homology model and the crystal structure of rat CYP24A1 is consistent with hydrophobic contact of Val-391 and the substrate side chain near C21. We interpret that the substrate specificity of V391L-modified human CYP24A1 toward 1α-OH-D3 is enabled by an altered contact with the substrate side chain that optimally positions C25 of the 1α-OH-D3 above the heme for hydroxylation. |
| Related Links | http://dx.doi.org/10.1074/jbc.m111.236679 |
| Ending Page | 28737 |
| Page Count | 9 |
| Starting Page | 28729 |
| File Format | |
| ISSN | 00219258 |
| e-ISSN | 1083351X |
| Journal | The Journal of Biological Chemistry |
| Issue Number | 33 |
| Volume Number | 286 |
| Language | English |
| Publisher | American Society for Biochemistry and Molecular Biology |
| Publisher Date | 2011-08-19 |
| Access Restriction | Open |
| Rights Holder | American Society for Biochemistry and Molecular Biology |
| Subject Keyword | Cell Biology Biochemistry Molecular Biology Research in Higher Education |
| Content Type | Text |
| Resource Type | Article |
| Subject | Cell Biology Biochemistry Molecular Biology |
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